diff --git a/README.md b/README.md
index c6095454..0131f345 100644
--- a/README.md
+++ b/README.md
@@ -40,6 +40,8 @@ cmake --build --preset win-amd64-relwithdebinfo
 
 The executable is placed at `out/build/win-amd64-relwithdebinfo/ac6recomp.exe`.
 
+On Windows, use the preset commands above rather than plain `cmake -L` in the repo root. If you previously configured from an `x86` Visual Studio prompt or with the wrong compiler on `PATH`, delete `out/build/win-amd64-relwithdebinfo` and re-run the preset from a normal 64-bit PowerShell/CMD window or an x64 Native Tools prompt.
+
 ## Modding Docs
 
 - [Texture Swap Modding Guide](docs/TEXTURE_SWAP_MODDING_GUIDE.txt)
diff --git a/setup_and_build.bat b/setup_and_build.bat
index ebe6976c..68cedd5b 100644
--- a/setup_and_build.bat
+++ b/setup_and_build.bat
@@ -56,6 +56,26 @@ if !sdk_found! equ 0 (
 echo [OK] All prerequisites found!
 echo.
 
+echo =========================================
+echo Environment Check
+echo =========================================
+if /I "%VSCMD_ARG_TGT_ARCH%"=="x86" (
+    echo [ERROR] Detected an x86 Visual Studio developer environment.
+    echo This project must be configured from an x64 environment.
+    echo Close this shell and reopen a normal 64-bit PowerShell/CMD window, or use an x64 Native Tools prompt.
+    pause
+    exit /b 1
+)
+if /I "%Platform%"=="x86" (
+    echo [ERROR] Detected Platform=x86 in the current shell.
+    echo This project must be configured for a 64-bit target.
+    echo Close this shell and reopen a normal 64-bit PowerShell/CMD window, or use an x64 Native Tools prompt.
+    pause
+    exit /b 1
+)
+echo [OK] No x86-only VS environment detected.
+echo.
+
 echo =========================================
 echo Git Branch Check
 echo =========================================
diff --git a/thirdparty/rexglue-sdk/CMakeLists.txt b/thirdparty/rexglue-sdk/CMakeLists.txt
index 6fdc0f0f..b76ad098 100644
--- a/thirdparty/rexglue-sdk/CMakeLists.txt
+++ b/thirdparty/rexglue-sdk/CMakeLists.txt
@@ -56,7 +56,12 @@ endif()
 
 # Enforce Clang18 compiler
 if(NOT CMAKE_CXX_COMPILER_ID STREQUAL "Clang")
-    message(FATAL_ERROR "ReXGlue requires Clang compiler. Please set CMAKE_CXX_COMPILER to clang++")
+    message(FATAL_ERROR
+        "ReXGlue requires Clang compiler.\n"
+        "  Detected compiler ID: ${CMAKE_CXX_COMPILER_ID}\n"
+        "  Detected compiler: ${CMAKE_CXX_COMPILER}\n"
+        "  Hint: configure this repo with its CMake preset instead of plain 'cmake -L',\n"
+        "        for example: cmake --preset win-amd64-relwithdebinfo")
 endif()
 
 if(CMAKE_CXX_COMPILER_VERSION VERSION_LESS "18.0")